Retatrutide is an experimental, unapproved weekly injection for obesity and type 2 diabetes that acts on three appetite and metabolism hormone sensors. Developer-funded trials showed large weight loss plus lower blood sugar, blood pressure, blood fats and liver fat; fewer heart attacks, strokes or slower aging have not been shown. Downsides: digestive effects, faster heart rate, skin sensations, some muscle loss and regain after stopping. Lean people are unstudied. (Full Review)
| Marker | Target | Why |
|---|---|---|
| HbA1c | 4.0–5.6% | Expected to fall |
| Fasting glucose | 70–99 mg/dL | Safety check: low values change diabetes drug doses |
| Lipid panel with apoB | Track change from own baseline | Expected to fall |
| ALT (pair with AST) | 7–56 U/L | Expected to fall with liver fat; safety check for liver injury |
| Creatinine with eGFR (pair with cystatin C) | Creatinine 0.6–1.3 mg/dL | Safety check: dehydration-related kidney injury |
| UACR | Track change from own baseline | Expected to fall |
| Resting heart rate | 60–100 beats per minute | Safety check: a sustained rise changes dose decisions |
| Blood pressure | Track change from own baseline | Expected to fall; safety check for hypotension |
| Lean mass by DXA | Track change from own baseline | Safety check: excess lean loss changes protein, training or dose |
| hsCRP | Track change from own baseline | Expected to fall |
| Pregnancy test (hCG) | Negative | Safety check before starting |
| Weight and waist size | Fat loss with preserved strength and function | Defines success |
Cadence: Weight, blood pressure and resting heart rate weekly at home during escalation; laboratory tests at 12 weeks, then every 3–6 months during active weight loss and every 6–12 months on a stable dose; body composition every 6–12 months. Severe abdominal pain, fainting or resting heart rate persistently above 100 beats per minute prompts medical review.